Which route is fastest but not suitable for all medications?

• A. Intravenous injection
• B. Intraosseous injection
• C. Intramuscular injection
• D. Sublingual

Answer: (A)

Getting a drug into the bloodstream as quickly as possible is the goal when immediate effect is needed. Intravenous administration achieves that by delivering the medication directly into a vein, so it enters systemic circulation without needing to cross absorption barriers. That makes the onset of action essentially immediate and the fastest route for a systemic effect. But this isn’t suitable for every medication. Some drugs irritate veins or can cause severe reactions if given too rapidly, so they must be infused slowly or delivered in a controlled rate. Others aren’t available in a stable or compatible IV formulation, or they require specific diluents or conditions that aren’t suitable for IV use. There are also risks unique to IV access, such as infection, phlebitis, air or particulate embolism, and fluid overload, and it demands sterile technique and careful monitoring. All of these factors mean intravenous administration, while the fastest, isn’t appropriate for every drug.